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    Determination of early spectral changes in melanoma cells during epoxomicin-induced apoptotic process
    (Refik Saydam National Public Health Agency (RSNPHA), 2021) Kucuksayan, Ertan; Sircan-Küçüksayan, Aslinur
    Objective: Determining the changes in the apoptosis process in cells can provide important information for new treatment and drug research. Apoptotic cells undergo a series of subcellular changes that lead to cell shrinkage and fragmentation. Determining these early changes in the apoptotic process depending on time may provide a new perspective to cell culture studies. The aim of this study is to develop a method in which early spectral changes occurring in the apoptosis process of melanoma cells can be determined depending on time. Methods: In this study, epoxomicin (Epo) was used to induce apoptosis in A375 melanoma cell line and apoptotic dose was determined by MTT method. In order to evaluate the early apoptotic process in a time-dependent manner, measurements were made at five different time points (0.5-6 hours) with a fixed Epo dose. DCFH-DA method was used to measure ROS, which is the most important stimulus of apoptosis. Bax amount was determined by Western Blot technique. Spectroscopic measurements were made with a back-reflection spectroscopy experiment setup consisting of spectrometer, tungsten-halogen light source and fiber optic probe. Apoptosis index values were determined from spectra. Results: Early spectral changes were determined with the spectra measured in the apoptosis time of melanoma cells. A significant difference was found in ROS measurements at 2, 4 and 6 hours compared to control. Cell viability was found to be 70% lower than control at 75 and 100 nM Epo doses after 24 hours. Time-dependent Bax levels were found to increase in all Epo groups as an indicator of apoptosis. Spectroscopic apoptosis index value was found to be compatible with ROS and Bax results at all groups. Conclusion: A new approach has been presented in which spectral changes occurring in the early stage of the apoptosis process in cell culture can be determined by back reflection spectroscopy. This approach has the potential to be developed in cell culture studies as a method that can monitor apoptosis over time without interfering with cell culture conditions. © 2021. All Rights Reserved.
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    Early detection onset of flap failure using near infrared spectroscopy
    (Taylor and Francis Ltd., 2022) Sircan-Küçüksayan, Aslinur; Özkan, Özlenen; Özkan, Ömer; Kucuksayan, Ertan; Ünal, Kerim; Canpolat, Murat
    Background: Near-infrared spectroscopy (NIRS) is widely used to assess flap perfusions by measuring tissue oxygen saturation (StO2). However, the StO2 level for the onset of perfusion failure is still a controversial issue. Aim: This study proposes a new threshold of StO2 level for detecting the onset of perfusion failure as early as possible to increase flap salvage rates. Methods: Twenty patients undergoing flap surgery were included in this study–13 flaps were implemented to cover defects that occurred due to trauma and 7 flaps to hide imperfections that occurred after cancer treatment. Thirteen flaps were in the lower extremity, six in the mandible, and one in the breast. NIRS was used to measure StO2 in 240 flap regions of the 20 patients to determine flap viability using descriptive statistics. Results: The mean StO2 values from healthy flap and control regions were obtained as 81.6% ± 0.36 and 82% ± 0.18, respectively. The lowest StO2 value of 77.2% was defined as the onset of a vascular complication at a probability of 99.74% by subtracting three times the standard deviation from the mean StO2 of healthy flaps. Vascular complications were observed from 21 regions in the four flaps with StO2 values lower than 77.2%, but only one was lost. Conclusion: The threshold value for the onset of perfusion failure was a 5% decrease from the expected value, much lower than previously described thresholds that may facilitate the detection of perfusion failure in the early stage and increase salvage rates in flap revisions. © 2021 Acta Chirurgica Scandinavica Society.